Electronic modules residing in a chassis or cabinet or other higher level assembly or system are often “edge cooled.” The typical electronic module includes a printed circuit board populated with electronic components. U.S. Pat. No. 4,962,444, for example, discloses a cold chassis including a frame with spaced ribs. Electronic modules are placed between the ribs. Coolant flows in the frame and ribs to cool the electronic modules. U.S. Published Patent Application No. 2005/0199372 discloses a cooling rib with machined cooling fins therein. Both of these references are incorporated herein by this reference.
In some cases, a radar system is one example, the equipment chassis is already designed and/or in place but higher power electronic modules (e.g., transmit/receive integrated microwave modules or TRIMMs) are to be installed. Changing the overall system architecture to include increased cooling for such modules may be expensive and thus undesirable.
Microchannel heat sinks are also known and, in one example, folded fins are inserted into a body and then brazing methods are used to secure the fins in place. During brazing, however, the microchannels formed by the fins can become clogged resulting in low yields. In addition, brazing autoclaves are limited in size. Brazing larger size heat sinks is expensive due to the limited availability of suppliers who have large brazing autoclaves and associated equipment.
Prior attempts to implement high-performance cooling schemes for edge-cooled electronic assemblies have had limited impact due to fundamental thermal physical and mechanical constraints preventing implementation on the scale necessary for edge cooling high power electronic systems. One thermal physical constraint includes the ability to fit the necessary volumetric flow of coolant into a constrained geometry and/or excessive temperature rises and pressure drops. An example of a mechanical constraint includes designs which cannot be easily scaled and/or manufactured. Many edge-cooled electronic systems are large and constitute many square meters which must be cooled. Practical large-scale solutions involving high performance cooling techniques such as the use of microchannels have proven elusive.